4K Blu-ray

Original Knockout Collection release had its 5.1 mix pitched too low, replacement disc and Ultimate Knockout Collection fixed the error. 

The Steelbook and UK standard edition are the same disc as the 2023 knockout collection.

Kino Lorber 4K Blu-ray's source is provided by Paramount has had DNR applied which affects the inherently soft looking film pretty strongly for at least a third of the running time

Criterion 4K Blu-ray; caps

The Criterion BD, which is sold separately, has a clunky encode unlike the Criterion UHD, even if it plays better in motion than the caps would suggest. Still, provided you're equipped to play 4K discs, UHD or bust for this one. https://slow.pics/c/hmDYlKgE

Arrow 4K Blu-ray is is a bit stronger than the very good Blue Underground The differences in the body of the film are negligible, but Arrow does have all three main credit sequences (Zombi 2, Zombie Flesh Eaters, and Zombie) that play in 4K via seamless branching. They also un-stabilized the handheld shot in the Zombie closing credits that Blue Underground had stabilized when they added new digital titles. It's back to looking properly handheld.

> Blue Underground 4K Blu-ray, "has the original Italy mono - think someone said earlier that the Blue Underground was a downmix on that track and the Arrow is corrected"

Kino Lorber 4K Blu-ray has terrible encoding, "chock-full of all the usual frozen grain, mushy grain, trailing grain, missing grain,..."

(Caveat: 15 seconds cut due to UK animal cruelty laws)